Assumption of Boron Trifluoride Hydrolyzation to Hydrogen Fluoride
and the Effect on Existing Monitoring Techniques
W. Ransom Jones - California Polytechnic State Univeristy (SSA Journal Volume 12 Number 1 - Spring 1998 pp. 19 - 23 )
Recently, the reliability of leak detection techniques for boron trifluoride gas BF3, has been called into question. Typically, boron trifluoride is monitored indirectly as hydrogen fluoride, HF, based on the assumption that BF3 instantly hydrolyzes to form HF upon contact with humid air. An understanding of the chemical reaction of anhydrous BF3 stored in gas cylinders and the environment into which it leaks is fundamental to any environmental health and safety program seeking to monitor it. This paper provides background to the assumption of hydrolization, the current question of sensor reliability, and a thorough examination of the chemical reaction. The discussion shows conclusively that HF is not formed as a result of BF3 exposure to moist air. The paper then discusses how this information affects four current gas monitoring techniques: Fourier Transform Infrared (FTIR) spectrometer; Molecular Emission Spectrometer (MES) or flame ionization; Mineral Acids Chemcassette (1) tapes; and electrochemical cells. It is deomonstrated that only the latter method is incapable of adequately monitoring BF3 due to its inherent reliance on the assumption of BF3 hydrolyzation to HF.